Chip inductor

ABSTRACT

Disclosed herein is a chip inductor. The chip inductor according to the present invention includes a substrate on which a trough-hole is formed, a conductive coil that is formed on the substrate, an upper resin composite magnetic layer that is filled to surround the conductive coil so that a core is formed on a center portion of the substrate, a lower resin composite magnetic layer that is formed on a bottom portion of the substrate, and an external electrode that is formed on both sides of the upper and lower resin composite magnetic layers.

CROSS REFERENCE(S) TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/907,808, filed May 31, 2013, which claims thebenefit under 35 U.S.C. Section 119 of Korean Patent Application SerialNo. 10-2012-0058289, entitled “Chip Inductor” filed on May 31, 2012,which is hereby incorporated by reference in its entirety into thisapplication.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a chip inductor, and more particularly,to a chip inductor in which a substrate on which a through-hole isprovided is built.

2. Description of the Related Art

In general, an inductor is a basic circuit element having a magneticinductance, and may include a coil and a core made of a magneticmaterial.

The inductor is one of the important passive elements constituting anelectronic circuit, together with a resistor and a capacitor, and isused as a component that removes noise or constitutes an LC resonancecircuit. The inductor may be structurally classified as a wire-woundinductor manufactured such that a coil is wound or printed on a ferritemagnetic body and electrodes are formed on both ends of the ferritemagnetic body, a laminated inductor manufactured such that an internalelectrode pattern is printed and laminated on an insulating sheet madeof a dielectric material or a magnetic material, and the like.

The inductor configured as above may be used in various systems such aslow-noise amplifiers, mixers, voltage controlled oscillators, matchingcoils, and the like. In particular, a planar inductor is an inductorelement that is implemented by a thin-film conductive coil formed on asubstrate, and may be used in a DC-DC converter, a noise filter, and thelike.

In recent years, in order to improve performance of the inductorelement, a technique for forming a magnetic body on the substratetogether with the thin-film conductive coil has been developed, and theperformance of the inductor is greatly affected by the characteristicsof the magnetic body such as a soft ferrite used inside the inductor,and the like.

In this instance, characteristics required for the magnetic body shouldhave sufficient transmittivity in a high frequency domain at the time ofhigh-frequency application, should not be thermally and mechanicallydeteriorated while the inductor is manufactured, and should be insulatedfrom the conductive coil.

RELATED ART DOCUMENTS Patent Documents

-   (Patent Document 1) Japanese Patent Laid-Open Publication No.    2000-243909

SUMMARY OF THE INVENTION

An object of the present invention is to provide a chip inductor inwhich a substrate is built to thereby enable the substrate to act as agap, and bias characteristics are improved by increasing a magnetic fluxdensity through a through-hole formed on the substrate.

According to an embodiment of the present invention, there is provided achip inductor, including: a substrate on which a through-hole is formed;a conductive coil that is formed on the substrate; an upper resincomposite magnetic layer that is filled to surround the conductive coilso that a core is formed on a center portion of the substrate; a lowerresin composite magnetic layer that is formed on a bottom portion of thesubstrate; and an external electrode that is formed on both sides of theupper and lower resin composite magnetic layers.

Here, the substrate may be made of a nonmagnetic material of resin or aceramic material.

In addition, the through-hole formed on the substrate may be formed inthe center portion of the substrate or four edges of the substrate.

In this instance, the substrate may have a thickness of 50 μm or less.

The upper and lower resin composite magnetic layers may be made of amixture of a metal magnetic material and a polymer material, or ferriteonly.

Here, when the upper and lower resin composite magnetic layers are madeof a mixture of a metal magnetic material and a polymer material, ametal powder may be mixed within the polymer to be evenly distributed.

In this instance, the polymer material may be epoxy, polyimide, LCP, andthe like.

Meanwhile, an insulating layer may further be formed outside theconductive coil. The insulating layer may be made of a polymer or otherresin materials each having insulation characteristics. This aims toenable the insulating layer to be insulated from metal powders includedin the upper resin composite magnetic layer in which the conductive coilis filled so as to be embedded.

The chip inductor configured as above may be extended in two directionssymmetrical to a quadrant of the substrate to thereby be electricallyconnected with the external electrode in which the conductive coilsurrounds side surfaces of the upper and lower resin composite magneticlayers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are cross-sectional views showing a process ofmanufacturing a chip inductor according to an embodiment of the presentinvention.

FIG. 2 is a plan view showing a substrate that is built in a chipinductor according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a chip inductor according toanother embodiment of the present invention.

FIG. 4 is a plan view showing a substrate applied to a chip inductoraccording to another embodiment of the present invention.

FIG. 5 is a plan view showing the results of the simulation to a chipinductor according to another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The acting effects and technical configuration with respect to theobjects of a chip inductor according to the present invention will beclearly understood by the following description in which exemplaryembodiments of the present invention are described with reference to theaccompanying drawings.

FIG. 1 is a cross-sectional view showing a process of manufacturing achip inductor according to an embodiment of the present invention, andFIG. 2 is a plan view showing a substrate that is built in a chipinductor according to an embodiment of the present invention.

As shown in the drawings, the chip inductor 100 according to the presentembodiment may include a substrate 110, a conductive coil 120 wound onthe substrate 110, an upper resin composite magnetic layer 130 formed onthe substrate 110 in such a manner that the conductive coil 120 isembedded, and a lower resin composite magnetic layer 140 formed on abottom portion of the substrate 110.

In addition, an external electrode 150 may be further formed on sidesurfaces of the upper and lower resin composite magnetic layers 130 and140 including the substrate 110.

The substrate 110 may be made of a nonmagnetic material using anonconductive material such as a resin material, a ceramic, or the like.Here, when the substrate 110 is made of the resin material, an FR4substrate or a polyimide substrate may be used, or other polymersubstrates may be used. In this instance, a thickness of the substrate110 may be preferably 50 μm or less. Here, when the thickness of thesubstrate 110 exceeds 50 μm, it is difficult to configure the thin-filmchip inductor, so that the chip inductor having the thickness which doesnot exceed 50 μm may be preferably designed.

In addition, the substrate 110 may include a through-hole 111 formed ona center portion thereof. The through-hole 111 may be shaped into acircuit, a square, etc., and the through-hole 111 is not limited to aspecific shape thereof other than the circle and square shapes, as longas the through-hole 111 can penetrate through top and bottom portions ofthe substrate.

The substrate 110 configured as above may support the conductive coil120 and the upper resin composite magnetic layer 130 which are formed ona top surface of the substrate 110 in a manufacturing process of thesubstrate 110, and act as a gap layer within the chip inductor aftermanufacturing the chip inductor.

The conductive coil 120 may be formed on a side surface of the uppersurface of the substrate 110 except the through-hole 111 formed on thecenter portion of the substrate 110. The conductive coil 120 may beformed in a scheme such as electrical plating, screen printing, or thelike, and may be configured in the form of a spiral coil made of copper.

By configuring the conductive coil 120 in the form of the spiral coil,low electrical resistivity and sufficient inductance may be ensured.

In addition, the conductive coil 120 may be configured in the form ofthe spiral coil, and may be laminated in a single or a plurality oflayers.

Meanwhile, the upper resin composite magnetic layer 130 may be coveredon the substrate 110, so that the conductive coil 120 is embedded. Theupper resin composite magnetic layer 130 may be preferably filled with asufficient height in which the conductive coil 120 can be embedded, andmay be made of only ferrite that is a magnetic material.

When forming the magnetic layer using the ferrite, ferrite plating maybe used, and a thickness of the magnetic layer may be accuratelycontrolled through a ferrite plating device in a spin spray scheme,thereby ensuring uniformity of the thickness. In addition, the spinspray scheme is performed at a relatively low temperature of 100° C. orless, and therefore a thermal effect with respect to the substrate 110or the conductive coil 120 may be minimized.

In addition, the magnetic layer may be made of any one of the metalmaterials such as Mo-permalloy, permalloy, Fe—Si—Al alloy, Fe—Si alloy,and amorphous other than the ferrite.

The upper resin composite magnetic layer 130 may be configured in such amanner that one metal powder selected from Fe, Ni, Zn, Co, Ba, Sr, andMn is distributed in the polymer. In this instance, the polymer may be aresin material such as epoxy, polyimide, LCP, etc.

In addition, the lower resin composite magnetic layer 140 by which abottom surface of the substrate 110 is covered may be formed on thebottom portion of the substrate 110. The lower resin composite magneticlayer 140 may be made of the same material as that of the upper resincomposite magnetic layer 130 formed on the substrate 110.

An insulating layer 160 surrounding an outer peripheral surface of theconductive coil 120 may be further formed inside the upper resincomposite magnetic layer 130 formed on the substrate 110, and preventthe conductive coil 120 made of Au or Cu from contacting with the upperresin composite magnetic layer 130 to be conducted.

That is, the insulating layer 160 may be formed when the upper resincomposite magnetic layer 130 is made of a material in which a metalmaterial is distributed and mixed in the polymer. The insulating layer160 may be made of a polymer having insulation characteristics and aresin material other than the polymer, and may be used to enable theconductive coil 120 to be insulated from the upper resin compositemagnetic layer 130 in which the metal powder is mixed.

Accordingly, when the upper resin composite magnetic layer 130 formed onthe substrate 110 is made of only an insulating material in which themetal power is not mixed, the insulating layer 160 may not be separatelyprovided.

An external electrode 150 may be formed on both sides of the chipinductor 100. The external electrode 150 is used to enable electricalconnection of the chip inductor 100, and may be formed by an electrodeformation process such as dipping or dispensing of solder, and the likeafter forming the upper and lower resin composite magnetic layers 130and 140 on the substrate 110.

In this instance, the external electrode 150 may be electricallyconnected with the conductive coil 120. The conductive coil 120 may beprovided in the form of a coil on both sides of a core of the upperresin composite magnetic layer 130 so as to be electrically connectedwith the external electrode 150, and may be extended to be symmetricalof both sides of a quadrant of the substrate with respect to the topsurface of the substrate 110. The conductive coil 120 extended to theoutside of the quadrant of the substrate 110 may be electricallyconnected with the external electrode 150.

The upper and lower resin composite magnetic layers 130 and 140 havehigh resistivity characteristics and high transmittivity. The upperresin composite magnetic layer 130 is formed in very close proximity tothe conductive coil 120, thereby improving quality characteristics ofthe chip inductor, and manufacturing the chip inductor having a thinthickness while implementing high inductance.

In the chip inductor 100 according to the present embodiment configuredas above, a direction of a magnetic path in the core formed in thecenter portion of the upper resin composite magnetic layer 130 formed onthe substrate 110 is exerted from the top of the substrate 110 to thebottom or from the bottom to the top through the through-hole 111 of thesubstrate 110, and thereby a magnetic flux density is increased withinthe chip inductor to thereby improve inductance, and characteristics ofa DC bias is improved.

Next, FIG. 3 is a cross-sectional view showing a chip inductor accordingto another embodiment of the present invention, and FIG. 4 is a planview showing a substrate applied to a chip inductor according to anotherembodiment of the present invention.

As shown in the drawings, as described above, the chip inductor 100according to the present embodiment may include the substrate 110, theconductive coil 120, and the upper and lower resin composite magneticlayers 130 and 140, and the external electrode 150 may be formed on bothsides of the upper and lower resin composite magnetic layers 130 and140.

In this instance, the same reference numerals refer to the samecomponents as those in the above described embodiment, and a detaileddescription thereof will be omitted.

According to the present embodiment, the substrate 110 that is built-inbetween the upper and lower resin composite magnetic layers 130 and 140should be made of a nonmagnetic material using a nonconductive materialsuch as a resin material or a ceramic material, and at least onethrough-hole 112 may be formed on four edges of the substrate 110.

As shown in FIG. 4, the through-hole 112 may be formed to be curvedtoward the center portion of the substrate 110, but may be formed inother shapes, that is, formed to be perpendicular to the center portion.The shape of the through-hole may be changed in accordance with adisposition of the conductive coil 120 formed on the substrate 110.

In addition, the chip inductor 100 according to the present embodimentmay be configured such that the through-hole is respectively formed onthe center portion of the substrate 110 and the four edges thereof.

In addition, a thickness of the substrate 110 may be preferably 50 μm orless so as to design the thin-shaped chip inductor. Here, the substrate110 may support the conductive coil 120 and the upper resin compositemagnetic layer 130 which are formed on a top surface of the substrate110, and act as a gap layer within the chip inductor after manufacturingthe chip inductor.

Meanwhile, the conductive coil 120 may be formed on the center portionof the top surface of the substrate 110 except the through-holes 112formed on the four edges of the substrate 110, formed in a scheme suchas electrical plating, screen printing, or the like, and preferablyconfigured in the form of a spiral coil made of copper.

The upper resin composite magnetic layer 130 may be formed on thesubstrate 110 on which the conductive coil 120 is formed, and the lowerresin composite magnetic layer 140 may be formed on a bottom portion ofthe substrate 110. In addition, the external electrode 150 that is usedfor electrical connection of the chip inductor 100 may be further formedon both side surfaces of the upper and lower resin composite magneticlayer 130 and 140 including the substrate 110.

In the chip inductor 100 according to the present embodiment configuredas above, a direction of a magnetic path of the upper and lower resincomposite magnetic layers 130 and 140 is exerted from the top of thesubstrate 110 to the bottom or from the bottom to the top through thethrough-holes 112 formed at the four edges of the substrate 110, andthereby a magnetic flux density is increased within the chip inductor tothereby improve inductance, and characteristics of a DC bias isimproved.

Meanwhile, results obtained when simulating characteristics of the chipinductor using the substrate 110 applied to the present embodiment areas follows.

As known from the results of the simulation shown in FIG. 5, the chipinductor according to the present embodiment has improved inductance(Ls) and characteristics of a DC bias for each Example compared to theconventional chip inductor in which the substrate is formed in a flatplate.

That is, compared to the conventional substrate, formed in the flatplate, having an inductance (Ls) of about 0.6 uH and a DC bias of 3.0 A,the chip inductor to which the substrate with the through-hole formedthereon is applied has an inductance of 0.85 to 1.05 uH in accordancewith the shape of the substrate in Examples 1 to 3, so that it can beseen that a capacity of the chip inductor is increased compared to theconventional chip inductor to which the flat plate-shaped substrate isapplied.

As set forth above, according to the embodiments of the presentinvention, in the chip inductor, the substrate is built in the chipinductor so as to support the conductive coil and act as a gap withinthe chip inductor, thereby manufacturing the chip inductor which iscompact and thinner.

In addition, by forming the through-hole on a predetermined position ofthe substrate built in the chip inductor, a magnetic flux density ofeach of the upper and lower resin composite magnetic layers is increasedthrough the through-hole, thereby implementing high inductance andimproving characteristics of the DC bias.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims. Accordingly, suchmodifications, additions and substitutions should also be understood tofall within the scope of the present invention.

What is claimed is:
 1. A chip inductor, comprising: a substrate on whicha through-hole is formed; a conductive coil that is formed on thesubstrate; an upper resin composite magnetic layer that is filled tosurround the conductive coil so that a core is formed on a centerportion of the substrate; a lower resin composite magnetic layer that isformed on a bottom portion of the substrate; and an external electrodethat is formed on both sides of the upper and lower resin compositemagnetic layers.
 2. The chip inductor according to claim 1, wherein thesubstrate is made of a nonmagnetic material of resin or a ceramicmaterial.
 3. The chip inductor according to claim 2, wherein thethrough-hole formed on the substrate is formed in the center portion. 4.The chip inductor according to claim 1, wherein the upper and lowerresin composite magnetic layers are made of a mixture of a metalmagnetic material and a polymer material.
 5. The chip inductor accordingto claim 1, wherein the upper and lower resin composite magnetic layersis made of ferrite or any one of metal materials of Mo-permalloy,permalloy, Fe—Si—Al alloy, Fe—Si alloy, and amorphous.
 6. The chipinductor according to claim 1, wherein an insulating layer is furtherformed outside the conductive coil, so that the upper resin compositemagnetic layer and the conductive coil are insulated from each other. 7.The chip inductor according to claim 1, wherein the conductive coil isextended in two directions symmetrical to a quadrant of the substrate tothereby be electrically connected with the external electrode.
 8. Thechip inductor according to claim 1, wherein at least one of thethrough-hole is further formed on four edges of the substrate.
 9. A chipinductor, comprising: a substrate on which at least one through-hole isformed at four edges thereof; a conductive coil that is formed on thesubstrate in the form of a spiral coil; an insulating layer that isformed outside the conductive coil; an upper resin composite magneticlayer that is filled to surround the conductive coil so that a core isformed on a center portion of the substrate; a lower resin compositemagnetic layer that is formed on a bottom portion of the substrate; andan external electrode that is formed on both sides of the upper andlower resin composite magnetic layers.
 10. The chip inductor accordingto claim 9, wherein the upper and lower resin composite magnetic layersare separated from each other with respect to the substrate to therebybe made of a mixture of a metal magnetic material and a polymermaterial, and are made of the same material.
 11. The chip inductoraccording to claim 9, wherein the substrate is made of a nonmagneticmaterial of resin or a ceramic material.
 12. The chip inductor accordingto claim 9, wherein the upper and lower resin composite magnetic layersare made of ferrite or any one of metal materials of Mo-permalloy,permalloy, Fe—Si—Al alloy, Fe—Si alloy, and amorphous.
 13. The chipinductor according to claim 9, wherein the conductive coil is extendedin two directions symmetric to a quadrant of the substrate to thereby beelectrically connected with the external electrode.
 14. The chipinductor according to claim 9, wherein the through-hole is furtherformed on the center portion of the substrate.